What is FMEA (Failure mode and effects analysis)?
Failure mode and effects analysis (FMEA; often written with “failure modes” in plural) is the process of reviewing as many components, assemblies, and subsystems as possible to identify potential failure modes in a system and their causes and effects.
For each component, the failure modes and their resulting effects on the rest of the system are recorded in a specific FMEA worksheet. There are numerous variations of such worksheets.
A FMEA can be a qualitative analysis, but may be put on a quantitative basis when mathematical failure rate models are combined with a statistical failure mode ratio database.
It was one of the first highly structured, systematic techniques for failure analysis.
It was developed by reliability engineers in the late 1950s to study problems that might arise from malfunctions of military systems. An FMEA is often the first step of a system reliability study.
A few different types of FMEA analyses exist, such as:
- Functional
- Design
- Process
Sometimes FMEA is extended to FMECA (failure mode, effects, and criticality analysis) to indicate that criticality analysis is performed too.
FMEA is an inductive reasoning (forward logic) single point of failure analysis and is a core task in reliability engineering, safety engineering and quality engineering.
A successful FMEA activity helps identify potential failure modes based on experience with similar products and processes—or based on common physics of failure logic.
It is widely used in development and manufacturing industries in various phases of the product life cycle. Effects analysis refers to studying the consequences of those failures on different system levels.
Functional analyses are needed as an input to determine correct failure modes, at all system levels, both for functional FMEA or piece-part (hardware) FMEA.
A FMEA is used to structure mitigation for risk reduction based on either failure mode or effect severity reduction, or based on lowering the probability of failure or both.
The FMEA is in principle a full inductive (forward logic) analysis, however the failure probability can only be estimated or reduced by understanding the failure mechanism.
Hence, FMEA may include information on causes of failure (deductive analysis) to reduce the possibility of occurrence by eliminating identified (root) causes.
What is DFMEA (Design Failure Mode and Effect Analysis) ?
DFMEA stands for “Design Failure Mode and Effect Analysis.” DFMEA is a methodical approach used for identifying potential risks introduced in a new or changed design of a product/service. The Design FMEA initially identifies design functions, failure modes and their effects on the customer with corresponding severity ranking / danger of the effect.
Then, causes and their mechanisms of the failure mode are identified. High probability causes, indicated by the occurrence ranking, may drive action to prevent or reduce the cause’s impact on the failure mode.
The detection ranking highlights the ability of specific tests to confirm the failure mode / causes are eliminated. The DFMEA also tracks improvements through Risk Priority Number (RPN) reductions.
By comparing the before and after RPN, a history of improvement and risk mitigation can be chronicled.
DFMEA is an indispensable product engineering tool for ensuring companies produce reliable products and services that satisfy customers in today’s competitive business landscape.
As previously mentioned, companies run DFMEA to reduce the number of design defects. Ideally, the process helps companies prevent any design-related problems from occurring at all. Anything that hinders a product from operating correctly is considered to be a “defect.”
The result? The consistent production, manufacturing, and output of high-quality deliverables. Companies involved in manufacturing, high-end technology, service delivery, and construction industries are the most likely to use DFMEA.
But organizations responsible for producing a variety of products and services also use the method for risk management. For these reasons, DFMEA is a vital part of total quality management processes.
DFMEA looks at potential design failures from all angles to determine what could hinder an intended product function from happening. It focuses on four areas of analysis:
- Failure Mode: The ways that a design-related failure could occur. For example, the laptop interface freezes when X number of programs are open for X number of hours.
- Failure Cause: The root cause of the failure mode could be a defect in a device’s design, system, quality, or part application.
- Failure Effect: The immediate consequences of the failure. For example, the frozen interface leads to a frustrating user experience.
- Severity of Failure: The severity of failure impacts productivity, quality, and safety. Quality engineers usually think in terms of worst-case outcomes.
In essence, DFMEA helps determine what might go wrong, how harmful the consequences would be and how to mitigate the failure modes before they occur.
DFMEA has helped many industries such as manufacturing, software development, healthcare, and food production take a proactive risk prevention and reduction approach.
FMEA VS DFMEA
FMEA stands for Failure Modes and Effects Analysis, which helps investigate asset, product and process failures as well as the effects of those failures. FMEA is the generic methodology from which DFMEA stems.
DFMEA stands for Design Failure Mode and Effects Analysis and is a type of FMEA, which looks at failures in the product design process and helps with the implementation of design controls.
Other subsets of FMEA include PFMEA or process FMEA. PFMEA stands for process failure mode and effect analysis and investigates process failures.
DFMEA is a type of FMEA, meaning that the only real difference is that DFMEA is solely related to the design stage, whereas FMEA covers a broader range of potential failures, including production and in-service.
DFMEA tends to be used mainly for products, while FMEA can also be used for processes, procedures and services.
The final major difference is that DFMEA tends to be much cheaper than performing FMEA at a later stage to correct a failure.
| FMEA | DFMEA | |
| Definition | Failure Mode Effects Analysis | Design Failure Mode Effects Analysis |
| Areas of Use | Used in manufacturing and engineering | A type of FMEA, mainly used for product design |
| Stage of Use | Used from design through to end-of-life for products, processes and services | Used in the design stage only |